It is frequently necessary during drilling or completion operations to conduct well bore logging activities. Such activities involve the use of a logging tool run into the well to evaluate the progress of the well's bore and to identify various characteristics of the earth formation adjacent the well bore. Logging operations are typically carried out by running various logging tools into the well using a variety of wire-line cables. Various other well servicing activities are often conducted using down-hole tools that are run into well bores or well casing using wire-line apparatus. When wells are being logged or completed on live wells, high-pressure conditions are often encountered. When such high pressures are encountered, wire-line pipe risers of significant height are often employed within the well derrick or above the well head in order to provide the wire-line pipe risers with sufficient length to house the down-hole tool and a sufficient length of weight bar to overcome the well pressure and thus pull the tool and its logging wire-line cable into the well bore. These wire-line risers incorporate grease wipers and/or wire-line packers in addition to various valves necessary to render the wire-line apparatus safe for containing the well's pressure.
Typically an open upper sheave is mounted above the wire-line riser and the wire-line cable being run into or exiting the well extends above the riser and passes around the upper sheave and thence downwardly to a lower sheave, near the drill floor level, in route to a wire-line cable winch, typically mounted on a wire-line service vehicle located adjacent the derrick. More recently, rather than providing extremely tall wire-line risers, especially where the height of the wire-line riser may be restricted, it has become customary to provide a pressure containing upper sheave. The upper sheave may be located at the upper end of a wire-line riser and incorporated therein to provide a grease seal conduit extending downwardly from the upper pressure-containing sheave head, thus providing a wire-line riser containing apparatus of sufficient length for efficient pressure containing capability but with approximately half the overall height. An example of a pressure-containing sheave disposed in pressure connection with a wire-line riser and a grease seal conduit is presented by U.S. Pat. No. 5,188,173 of Richardson, et al, and U.S. Pat. No. 5,662,312 of Leggett, et al. These types of pressure-containing sheaves have deficiencies in that they are restricted relative to their weight and pressure containing capability due to the significant area of the housings. The housings are also subject to considerable pressure induced side loading that, especially under high-pressure conditions, can significantly distort the body structure to the extent that the sheaves can become inoperative. It is therefore desirable to provide a light weight, radial pressurized wire-line cable conveyance mechanism having high pressure capability for wire-line well servicing apparatus and other completion activities utilizing wire-line services that are also configurable to produce multiple radial bends that reduce or eliminate the need for open or closed sheaves all together.